Backyard wild birds come in all shapes and sizes. They eat nuts, seeds, berries, fruit, and insects. They welcome wintertime sprinklings of seeds in the snow. You may think that birds are light eaters, but it is quite the opposite. They are actually big eaters. Wild birds need plenty of food to produce the energy their bodies require to maintain a fast metabolism. This fast metabolic rate allows them to fly. Finches love thistle, in fact, thistles are special plants to finches. They feed their young on the immature fruit. These plants also produce "floss". This floss comes from the flowers that have gone to seed and left their fluffy seed heads behind. Finches frequently select thistles' floss for structural and lining materials for their nests. Often thistles mature before the finches nest, thus providing them with fresh new floss. Some thistle heads never open completely, which traps last year's floss, making the product readily available for an energetic finch. An imported thistle "niger" seed, from Africa and Asia, is high in protein and fat. It has an added bonus value of not attracting squirrels or blackbirds.